Dielectric response of particles in flowing media: the effect of shear-induced rotation on the variation in particle polarizability

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DOIResolve DOI: http://doi.org/10.1103/PhysRevE.84.011922
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TypeArticle
Journal titlePhysical Review E - Statistical, Nonlinear, and Soft Matter Physics
ISSN1539-3755
Volume84
Issue1
Article number11922
SubjectAxisymmetric; Cytometry; Dielectric particles; Dielectric response; Dielectrophoretic; Experimental measurements; External electric field; External fields; Field flow fractionation; Flow based; Flow impedances; Flowthrough; Individual particles; Liquid suspension; Nonspherical particle; Parabolic velocity profile; Polarizabilities; Signal amplitude; Spherical symmetry; T-lymphocytes; Electric fields; Fractionation; Liquid chromatography; Polarization; Rotation; Screening; Shear flow; Uncertainty analysis; Suspensions (fluids)
AbstractWhen particles in liquid suspensions flow through channels and pipes in a laminar fashion, the resulting parabolic velocity profile gives rise to shear, which induces the particles to rotate. If flowing suspensions containing dielectric particles are immersed in an external electric field, the anisotropic polarization induced in rotating nonspherical particles will vary with the orientation of the particle with respect to the external field; what results is an uncertainty in experimental measurements that involve particle polarization. The present study establishes the limits of this uncertainty and shows that departure from spherical symmetry in individual particles can lead to a significant overlap in measurements attempting to discriminate between particle subpopulations in suspensions. For example, the uncertainty in signal amplitude for a population of activated T-lymphocytes can be as high as 20%. Such concerns arise in applications like field-flow fractionation, dielectrophoretic sorting of particles, flow impedance measurements and cytometry, and, most recently, isodielectric separation, all of which are used to separate particles in a flow based on their dielectric response. This paper considers axisymmetric particles as the first departure from the approximation of spherical symmetry, shows how to calculate an estimate of the size of the population overlap, and suggests possible strategies to minimize it. © 2011 American Physical Society.
Publication date
LanguageEnglish
AffiliationNational Research Council Canada (NRC-CNRC); National Institute for Nanotechnology
Peer reviewedYes
NPARC number21271945
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Record identifiera225fb98-77a8-498e-ac55-88a9c701877a
Record created2014-05-13
Record modified2016-05-09
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